THE E-ELT DESIGN REFERENCE MISSION

EXECUTIVE SUMMARY

The E-ELT Design Reference Mission (DRM) encompassed a detailed,
hands-on exploration of a selected sample of science cases through the
analysis of simulated E-ELT data. The purpose of this exercise was (i)
to provide a quantitative assessment of the extent to which the E-ELT
will be capable of addressing key scientific questions, (ii) to assist
the project in making critical trade-off decisions by quantifying
their consequences in terms of scientific gains and losses, and (iii)
to support the development of the E-ELT Science Case. The overarching
aim of the DRM was to help ensure that the E-ELT will be aligned with
the scientific aspirations of its community as much as possible.

In summary, the DRM simulations have provided quantitative evidence of
the transformational nature of the science programme envisioned for
the E-ELT: the E-ELT will undoubtedly revolutionise several fields of
astrophysics. However, the simulations have also demonstrated that a
fair fraction of this programme lies at the edge of feasibility,
leading to the conclusion that much of the science encapsulated by the
DRM will indeed require a 40m-class telescope. In addition, the
simulations have verified that the site chosen for the E-ELT conforms
to the science plans, and that almost none of the capabilities
required by these science cases are missing from current adaptive
optics and instrumentation plans.

Brief overview

The science cases studied by the DRM were
selected by the E-ELT SWG for being prominent
examples highlighting the key capabilities of the telescope. Although
they cover a wide range of science topics they were not intended to be
an exhaustive list of the science that the E-ELT will do. The choice
of programs also does not necessarily reflect the expected instrument
suite.

The DRM process began with members of the SWG (with help from
the community) drafting a 'DRM proposal' for each of the DRM science
cases. These proposals were written somewhat in the manner of a
regular ESO observing proposal: they briefly
summarised the science case and then described a more or less
well-defined set of E-ELT observations designed to address the
scientific question at hand.
The key task of the DRM was to answer, for each science case, the
following two questions:

What precisely can be achieved with the observations described
in the proposal in a given amount of observing time, or, vice versa,
how much observing time is needed to achieve a given set of science
goals?

How do these results depend on the
properties of the telescope, the instrument, the AO performance and/or
the site? Which features of the E-ELT system are critical to the
success of the proposal? What is the limiting factor?

followed by:

Identification of key requirements for each case and quantification of
the scientific losses in case the requirements cannot be met, thus
helping the project to understand the scientific consequences of any
trade-off decisions.

The nature of the chosen DRM cases and/or of the questions was such
that they could not usually be answered by a straightforward
signal-to-noise consideration. Instead, they required an appropriately
realistic simulation of the data 'requested' in the proposals and
subsequent analysis. This then constituted the main body of work
carried out within the framework of the DRM: the provision of a suite
of simulated E-ELT data, their quantitative scientific analysis, and
the exploration of scientific and technical parameter spaces in order
to identify the critical aspects of each science case. This work was
carried out by various members of EScO
in collaboration with the SWG.

The simulations required both scientific and technical input. The
scientific input was provided by, or agreed upon with, the responsible
SWG member. On the technical side, a large number of inputs regarding
the characteristics of the telescope, the site, the AO performance,
etc., were required. In order to create as much homogeneity across the
whole DRM as possible these data were compiled during the first stages
of the DRM and collected in a central technical
data repository. The simulations used these common data whenever
possible.

DRM Workshops

The DRM process and simulation results were discussed with interested
members of the community, various instrument study teams and members
of the Science Working Group at two DRM
workshops in 2008 and 2009.

DRM Report

The final DRM Report provides a
comprehensive description of the entire DRM. In particular it
includes an account of the DRM process, detailed descriptions of the
work carried out for each of the DRM cases, a summary of the results
for each case, and the overall conclusions. The original DRM proposals
are also included.